English
The NNNorm of f.prod g equals the NNNorm of the pair: ||f.prod g||_nn = ||(f, g)||_nn.
Русский
NNNorm произведения равен NNNorm пары: ||f.prod g||_nn = ||(f, g)||_nn.
LaTeX
$$$$\\|f.prod g\\|_{\\!nn} = \\|(f, g)\\|_{\\!nn}.$$$$
Lean4
/-- The operator norm of the second projection `E × F → F` is at most 1. (It is 0 if `F` is zero, so
the inequality cannot be improved without further assumptions.) -/
theorem norm_snd_le : ‖snd 𝕜 E F‖ ≤ 1 :=
opNorm_le_bound _ zero_le_one (fun ⟨e, f⟩ ↦ by simpa only [one_mul] using le_max_right ‖e‖ ‖f‖)